Structural building walls, such as foundation walls, and interior walls can be damaged, or even fail, if exposed to water for a prolonged period of time. Water may be present in liquid or gas phase, such as in moisture or vapor form.
Small to moderate amounts of moisture typically can escape without causing damage. Recent building techniques, however, have been sealing walls with vapor barriers. At the same time such seals can trap even small amounts of moisture, which in turn may cause damage.
For example, it is now increasingly common to thermally insulate basement walls, and consequently to install moisture and vapor barriers on one or both sides of the walls. While the moisture and vapor barriers can prevent outside moisture from getting into the walls through the sides, they can also trap any moisture that has migrated into the wall.
Leakage water can be drained through drain conduits, as described, for example, in U.S. Pat. No. 5,845,456 to Read, issued Dec. 8, 1998 (“Read”).
However, even when drainage is used, water damage can still occur in building walls, particularly basement walls with full height thermal insulation.